I just changed my thermostat. Replaced it with a stock 180 stat. I did this because someone mentioned that my old one was stuck because the top hose that goes to the thermostat housing was always "sucked in". Well I changed the stat and when the car is warm the coolant is flowing through the hose and rounds it back out. When it cools off it goes back to the sucked in look again. Is this normal? If not what do I do to fix it? FWIW, i have topped off the coolant level and bled the system.

On another note, I never hear my fans turn on. If I turn the AC on the fans come on. When I am driving around town, my gauge hovers at about the halfway mark. When I am in alot of stop-go/drive-thru's the gauge goes all the way up to 3/4. When it does this i don't hear any fans come on, so I kick the AC on to get it back to the 1/2 mark.

I need whatever advice I can get to help me out. Being that it is 110 deg plus here everyday, I would like to make sure my car doesn't overheat. If it helps any I do get the phantom low coolant light randomly even though my coolant level is fine.

TIA for your help.

 

it would make sense to me that if your top hose is getting sucked in when your car is cool that you have a problem with your coolant recovery system

if your radiator cap is messed up or the tube running to your recovery tank is plugged i could see a hose getting sucked in when the car is cool

 

So what would I need to do to diagnose the prob or how to fix it? Should I just buy a new rad cap? Also How do i check the tube to the tank? The level in the tank fluctuates with the temp of the motor.

 

When the radiator cools down, the coolant volume contracts, crearing a vacuum. In a properly functioning system, the vacuum relief spring in the radiator cap opens, and the vacuum sucks coolant if from the overflow reservoir.

If your upper hose is collapsing, there are two possibilities.

1 - The radiator cap vacuum relief spring is not opening, or the hose from the radiator overflow to the reservoir is plugged up - both of these as indicated in the first response above. First check the hose from the radiator kneck overflow to the reservoir, and make sure it is not plugged up. If its clear, get a new cap.

2 - The upper hose has been weakened by age, or the previous problem with the t'stat damaged it, and it can not stand up to even the smallest amount of vacuum, which will exist just to pull coolant up from the reservoir. If you work your way through 1, and its still a problem, you will have to replace the radiator hose.

 

Thanks for all the advice. Now I have discovered a bigger problem and need to know why it's happening. Yesterday when I got the Z to the house I popped the hood to start looking over the system and wait for it to cool off. I looked at the hose going to the thermostat and it was swollen up twice the size it should be and was hard as a rock. I have included a pic. Why would this be happening? I'm afraid to drive it right now for fear of a blow out. I know that I need to replace the hose, but a bad hose can cause this?

I was also thinking that I might have been given the wrong thermostat (SBC/LT1). I got a stant pt#65218 from Checker. I have also included a pic of this. One thing I noticed is that on the Stant there is a 1/4" brass/copper cylinder like piece that hangs from the top of the stat and moves up/down. In shboxs picture of the LT1 stat I did not see that piece so I might have the wrong stat?? Any info on the stat or why this hose would be so swollen would help me out. I might throw in the towel and just take it to the shop and have them deal with it. Before I do that I would like to have an idea on whats going on. Thanks.

The hose in question (sorry it was a cell phone pic)
You can see how swollen it is.


The stat I bought


PLEASE HELP!!!

 

They should not have the same part for SBC and LT1. LT1s have reverse flow cooling and take a different thermostat. Did you keep your old thermostat? You might want to put it back in, replace the rad. cap and hose if necessary and see how it all works.

 

The old thermostat was stuck, so no I don't have it. Replacing the cap and hose is a definate. The swollen hose has me extremely worried. I am trying to figure out why it's doing it so I can get it all done at the same time.

 

Where's everyone at??

 

EnFuegoZ28:
The thermostat you have pictured IS the LT1 style. Perhaps the hose wall has been weakened by age and the collapsing problem. You must do the hose and the cap ... check the other hoses too ... if one is bad the rest may not be far behind. Places like Summit Racing sell quality hose sets for your car online. (you need to reuse some of the metal connectors and restrictor from the old heater hoses)
Good Luck

 

Thanks, I looked at summit and some some hose kits. I also looked at the rad caps and for the LT1 all they have listed are 16psi caps. My stock cap says 18 psi. I should stay with the 18 psi right??

Hopefully changing the hoses, rad cap, and a flush will take care of my probs. (fingers crossed)

 

That big, white, bulging thing is the hose? Replace it, now!

Yes, stay with the 18 psi cap.

 

Thats exactly what I thought when I popped the hood. LOL. Yes I will be replacing the hose and the cap. With a flush and flow check hopefully this will be the end of it. As far as the 18psi cap, why doesn't summit carry them?? Seems odd.

I will be also trying to find out why my fans won't turn on (even though my temp got to 3/4 on the gauge). They will run if I have my AC on though. I've searched and can't find a troubleshooting guide for it. Maybe you can direct me to the right place shoebox??

 

You should be able to find the correct cap at any auto parts store. Probably have the hose too.

You keep begging for help.... but I basically told you what needed to be done yesterday.

 

There is all kinds of cooling system testing info on my Tech Page in the How To's section.

 

I'm sorry if it seems repeatative. I was going to take your advice but when I saw how much pressure had built up and how swollen the hose got I thought I might have a different problem. I was just trying to make sure that it wasn't anything more serious.

Today I will be changing out the hose and the cap. Then a flow check and flush will be done. Then hopefully I will be done with it. Thanks for the replies and we'll see what happens.